Veterinary Homeopathy: Why Are We Still Talking about This?

Introduction
In two years of writing my Veterinary Practice News column about evidence-based medicine, I have largely managed to avoid the subject of homeopathy. It is the classic example of a medical practice developed before a scientific understanding of the basic mechanisms of health and disease existed, and it has remained true to 18th-century principles despite all of the subsequent advances in medical knowledge. Controversial from its beginnings,1 homeopathy has long been employed by only a few healthcare professionals, and surveys show only a tiny minority of citizens in most developed countries have used homeopathic treatment.2–4

It would seem safe, then, to dismiss and ignore this relic of pre-scientific medicine. However, homeopathy has managed to retain a small following in both human and veterinary medicine, and its proponents are sometimes visible and influential out of proportion to their numbers. Clients often ask me about using homeopathic remedies they have heard about from friends or online, often from veterinarians who support the practice. 

What is more, misleading information about homeopathy continues to be presented at major veterinary continuing education conferences and to appear in niche alternative veterinary medicine journals, which helps to create doubt about the scientific evidence concerning this practice. Attempts by regulators and professional organizations to discourage the use of homeopathy have had mixed results, thanks to vigorous lobbying against the scientific consensus by a vocal minority. Therefore, a brief evidence-based overview of veterinary homeopathy may still be useful to pet owners and veterinary professionals.

Basic Principles
The first rule of homeopathy is that something which causes certain symptoms in a healthy person is the best treatment for those symptoms in someone who is sick, a principle known as the Law of Similars.5 This clearly reflects a metaphorical approach to disease which, in modern medical science, has been replaced by specific pathophysiologic explanations derived from scientific research. Apart from this flaw, however, the Law of Similars has the obvious problem that if you give an ill patient something which creates symptoms of illness in normal individuals, you will often make them worse! 

Samuel Haahnemann, the inventor of homeopathy, discovered this problem through trial and error with his own patients.5,6 Instead of recognizing that his basic principle was flawed, however, he took the approach of greatly diluting his remedies, which reduced their ill effects. In the absence of the harm done by the traditional remedies used at the time, many of which were toxic to some degree, some of Hahnemann’s patients recovered after taking his diluted preparations. Since the only evidence available at the time for assessing efficacy was anecdote and subjective experience, this was interpreted as successful treatment.

This “success” led Hahnemanns to the second foundational principle of homeopathy, the principle of Potentization by Dilution and Succussion. This principle states that homeopathic medicines become more potent the less active ingredient they contain. (Succussion refers to shaking the remedies, since Hahnemann apparently also believed that the agitation his medicines received as he travelled on horseback to see his patients somehow increased their curative power.)5,6

Finally, homeopathy relies on a complex process for individualizing the use of homeopathic preparations by evaluating the physical and mental experiences of patients and comparing them with experiences reported by healthy individuals testing specific homeopathic remedies. The details of this process are too involved to summarize here, but they involve a purely subjective and anecdotal process that has not been, and probably cannot be, validated through controlled scientific research.

The Scientific Evidence
Despite the inherent implausibility of these concepts and the general incompatibility of homeopathic theory with established principles of physiology, chemistry, pharmacology, and other modern disciplines in medical science, there has been a lot of pre-clinical and clinical research on homeopathic remedies and treatments. The majority of this has been published in journals devoted exclusively to homeopathy of other alternative therapies, and there is often a lack of proper methodological controls and significant risk of bias in these publications. Numerous systematic reviews of homeopathy in human medicine have been published, and the majority show no evidence of real or clinically meaningful effects beyond that of placebos.2,7-35 When sufficient studies are conducted and published by committed advocates for any practice, bias will inevitably lead to some apparently positive results, but such results have not been replicated or validated by consistent, unbiased investigation.

The veterinary literature concerning homeopathy is, as always, sparser than that in human medicine, but the same general assessment applies. Despite some ostensibly positive findings in low-quality studies with high residual bias risk, the preponderance of the evidence shows no real or replicable effects. Even dedicated proponents of homeopathy are unable to find convincing high-quality research evidence for the practice when they apply accepted methods for evaluating the literature.36–42

Evidence-based medicine is always about a flexible and probabilistic understanding, and absolute, immutable conclusions are anathema to the core principles of this approach. However, evaluating homeopathy at every level, from biologic plausibility to pre-clinical and in vitro research to clinical trials leads to as confident a conclusion as science can ever muster, which is that the practice has no benefits.

The Future of Veterinary Homeopathy
It seems clear, given this scientific conclusion, that homeopathy can have no legitimate role in modern veterinary medicine. It is unethical to offer clients ineffective remedies, and even when the treatments themselves may do no harm they can mislead clients and discourage the use of truly effective treatments. 

A number of regulators and professional organizations have recognized this and taken action. The Federal Trade Commission and the Food and Drug Administration have recently issued statements warning the public that claims for the safety and efficacy of homeopathy are not supported by science. In the veterinary field, the Australian Veterinary Association, British Veterinary Association, and the Royal College of Veterinary Surgeons all have clear policy statements acknowledging homeopathy as ineffective and discouraging its use. Numerous specialty colleges in the U.S. and abroad have issued similar statements. The American Veterinary Medical Association, unfortunately, declined to adopt a similar policy in 2014 despite a finding from its own Council on Research that, “there is no clinical evidence to support the use of homeopathic remedies for treatment or prevention of diseases in domestic animals.”43

Political and economic considerations, as well as vehement advocacy and misleading information from proponents of homeopathy, have kept the method alive despite the clear scientific evidence against it. Hopefully, the current trend towards accepting the verdict of science will continue, and homeopathy will continue to decline and eventually disappear from veterinary journals and continuing education. Undoubtedly, some practitioners and clients will always choose anecdote and wishful thinking over evidence, but as members of a scientific medical professional, we have a responsibility to provide effective care for our patients and honest, accurate information for our clients. Meeting this core ethical responsibility leaves no place for equivocation or failing to clearly discourage the use of homeopathy.

References

1.        Holmes OW. Homeopathy and Its Kindred Delusions: Two Lectures Delivered before the Boston Society for the Diffusion of Useful Knowledge. Boston, MA: William D. Ticknor; 1842.

2.        Banerjee K, Mathie RT, Costelloe C, Howick J. Homeopathy for Allergic Rhinitis: A Systematic Review. J Altern Complement Med. 2017;23(6):426-444. doi:10.1089/acm.2016.0310

3.        Alexander H. Parents guilty of manslaughter over daughter’s eczema death. Sydney Morning Herald. https://www.smh.com.au/national/parents-guilty-of-manslaughter-over-daughters-eczema-death-20090605-bxvx.html. Published June 5, 2009.

4.        Su D, Li L. Trends in the use of complementary and alternative medicine in the United States: 2002-2007. J Health Care Poor Underserved. 2011;22(1):296-310. doi:10.1353/hpu.2011.0002

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6.        Bradford TL. The Life and Letters of Dr. Samuel Hahnemann. Philadelphia, PA: Boericke & Tafel; 1895. https://archive.org/details/lifelettersofdrs00brad/page/n11.

7.        Barnes J, Resch KL, Ernst E. Homeopathy for postoperative ileus? A meta-analysis. J Clin Gastroenterol. 1997;25(4):628-633. http://www.ncbi.nlm.nih.gov/pubmed/9451677. Accessed November 12, 2018.

8.        Ernst E, Barnes J. Are homoeopathic remedies effective for delayed-onset muscle soreness: a systematic review of placebo-controlled trials. 1998. https://www.ncbi.nlm.nih.gov/books/NBK67320/. Accessed November 12, 2018.

9.        Ernst E, Pittler MH. Re-analysis of previous meta-analysis of clinical trials of homeopathy. J Clin Epidemiol. 2000;53(11):1188. http://www.ncbi.nlm.nih.gov/pubmed/11186614. Accessed November 12, 2018.

10.      Ernst E, Pittler MH. Efficacy of homeopathic arnica: a systematic review of placebo-controlled clinical trials. Arch Surg. 1998;133(11):1187-1190. http://www.ncbi.nlm.nih.gov/pubmed/9820349. Accessed November 12, 2018.

11.      Ernst E (Edzard). Homeopathy?: The Undiluted Facts?: Including a Comprehensive A-Z Lexicon. Cham?: Springer International Publishing?:;Imprint: Springer,; 2016.

12.      Ernst E. Homeopathy – The Undiluted Facts. Cham: Springer International Publishing; 2016. doi:10.1007/978-3-319-43592-3

13.      Fisher P, Dantas F. Homeopathic pathogenetic trials of Acidum malicum and Acidum ascorbicum. Br Homeopath J. 2001;90(3):118-125. doi:10.1038/sj/bhj/5800476

14.      Goodyear K, Lewith G, Low JL. Randomized double-blind placebo-controlled trial of homoeopathic “proving” for Belladonna C30. J R Soc Med. 1998;91(11):579-582. http://www.ncbi.nlm.nih.gov/pubmed/10325874. Accessed November 12, 2018.

15.      Hirst SJ, Hayes NA, Burridge J, Pearce FL, Foreman JC. Human basophil degranulation is not triggered by very dilute antiserum against human IgE. Nature. 1993;366(6455):525-527. doi:10.1038/366525a0

16.      Jonas WB, Linde K, Ramirez G. Homeopathy and rheumatic disease. Rheum Dis Clin North Am. 2000;26(1):117-123, x. http://www.ncbi.nlm.nih.gov/pubmed/10680199. Accessed November 12, 2018.

17.      Linde K, Clausius N, Ramirez G, et al. Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled trials. Lancet (London, England). 1997;350(9081):834-843. http://www.ncbi.nlm.nih.gov/pubmed/9310601. Accessed November 12, 2018.

18.      Becker-Witt C, Weißhuhn TER, Lüdtke R, Willich SN. Quality Assessment of Physical Research in Homeopathy. J Altern Complement Med. 2003;9(1):113-132. doi:10.1089/107555303321222991

19.      Linde K, Melchart D. Randomized controlled trials of individualized homeopathy: a state-of-the-art review. Altern Complement Ther. 1998;4(6):371-373. doi:10.1089/act.1998.4.371

20.      Linde K, Scholz M, Ramirez G, Clausius N, Melchart D, Jonas WB. Impact of study quality on outcome in placebo-controlled trials of homeopathy. J Clin Epidemiol. 1999;52(7):631-636. http://www.ncbi.nlm.nih.gov/pubmed/10391656. Accessed November 12, 2018.

21.      Long L, Ernst E. Homeopathic remedies for the treatment of osteoarthritis: a systematic review. Br Homeopath J. 2001;90(1):37-43. http://www.ncbi.nlm.nih.gov/pubmed/11212088. Accessed November 12, 2018.

22.      McCarney RW, Linde K, Lasserson TJ. Homeopathy for chronic asthma. Cochrane Database Syst Rev. 2004;(1):CD000353. doi:10.1002/14651858.CD000353.pub2

23.      Moffett JR, Arun P, Namboodiri MAA. Laboratory research in homeopathy: con. Integr Cancer Ther. 2006;5(4):333-342. doi:10.1177/1534735406294795

24.      Ovelgönne JH, Bol AW, Hop WC, van Wijk R. Mechanical agitation of very dilute antiserum against IgE has no effect on basophil staining properties. Experientia. 1992;48(5):504-508. http://www.ncbi.nlm.nih.gov/pubmed/1376282. Accessed November 12, 2018.

25.      Shang A, Huwiler-Müntener K, Nartey L, et al. Are the clinical effects of homoeopathy placebo effects? Comparative study of placebo-controlled trials of homoeopathy and allopathy. Lancet (London, England). 2005;366(9487):726-732. doi:10.1016/S0140-6736(05)67177-2

26.      Vickers AJ. Independent replication of pre-clinical research in homeopathy: a systematic review. Forsch Komplementarmed. 1999;6(6):311-320. doi:10.1159/000021286

27.      Vickers A, McCarney R, Fisher P, van Haselen R. Can homeopaths detect homeopathic medicines? A pilot study for a randomised, double-blind, placebo controlled investigation of the proving hypothesis. Br Homeopath J. 2001;90(3):126-130. doi:10.1038/sj/bhj/5800475

28.      Walach H, Köster H, Hennig T, Haag G. The effects of homeopathic belladonna 30CH in healthy volunteers — a randomized, double-blind experiment. J Psychosom Res. 2001;50(3):155-160. http://www.ncbi.nlm.nih.gov/pubmed/11316508. Accessed November 12, 2018.

29.      Cucherat M, Haugh MC, Gooch M, Boissel JP. Evidence of clinical efficacy of homeopathy. A meta-analysis of clinical trials. HMRAG. Homeopathic Medicines Research Advisory Group. Eur J Clin Pharmacol. 2000;56(1):27-33. http://www.ncbi.nlm.nih.gov/pubmed/10853874. Accessed November 12, 2018.

30.      Dantas F, Fisher P, Walach H, et al. A systematic review of the quality of homeopathic pathogenetic trials published from 1945 to 1995. Homeopathy. 2007;96(1):4-16. doi:10.1016/j.homp.2006.11.005

31.      Endler P, Thieves K, Reich C, et al. Repetitions of fundamental research models for homeopathically prepared dilutions beyond 10(-23): a bibliometric study. Homeopathy. 2010;99(1):25-36. doi:10.1016/j.homp.2009.11.008

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33.      Ernst E. Homeopathic prophylaxis of headaches and migraine? A systematic review. J Pain Symptom Manage. 1999;18(5):353-357. http://www.ncbi.nlm.nih.gov/pubmed/10584459. Accessed November 12, 2018.

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36.      Doehring C, Sundrum A. Efficacy of homeopathy in livestock according to peer-reviewed publications from 1981 to 2014. Vet Rec. 2016;179(24):628. doi:10.1136/vr.103779

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5 Responses to Veterinary Homeopathy: Why Are We Still Talking about This?

  1. Lorin D Lawrence, dvm says:

    Thank you, Brennen, for getting this info into print. Homeopathy always sounded like “snake oil” to me. How could a treatment get stronger with successive dilutions? As PT Barnum said, ‘there is a sucker born every minute. ‘

  2. Greg Nutt says:

    So, in your opinion and based on the evidence, why are we still talking about homeopathy? Why would anybody offer this as a treatment modality?

  3. skeptvet says:

    Despite proven lack of efficacy, the appeal of homeopathy persists for many reasons. For one, anecdote is still the predominant way most pet owners, and even most veterinarians, judge efficacy, and ineffective therapies can easily look like they are helping due many placebo and other non-specific effects. There is a general distrust of science and scientific medicine as well as a lack of scientific literacy, and these support many quack therapies such as homeopathy. You will find quite a few articles here discussing why ineffective therapies seem to work and why people choose them despite evidence against their benefits. Here are just a few:

    Placebos in Veterinary Medicine

    Why do ineffective treatments seem helpful? A brief review

    Why Smart People Believe Weird Things

  4. skeptvet says:

    Yes, homeopathy and Ayurvedic medicine are fairly popular in India. The lack of access to conventional medical care may play a role in this, but there are obviously cultural factors as well. Unfortunately, such popularity does not have any bearing on the effectiveness of the treatments, and the recommendation of homeopathy for coronavirus is a terrifyingly dangerous one.

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